How can you select materials for equipment in explosive environments?

Selecting the right materials for equipment in explosive environments is a crucial task for chemical engineers. Explosive environments are those where flammable gases, vapors, dusts, or fibers can form explosive mixtures with air or oxygen. Equipment that operates in such conditions must be able to withstand high pressures, temperatures, shocks, and corrosion, as well as prevent ignition sources and electrostatic discharge. In this article, we will discuss some of the factors and standards that you should consider when choosing materials for piping and valves in explosive environments.

1 Material properties

The first step in the process is to evaluate the material properties that are relevant for the equipment performance and safety. Of particular importance are mechanical strength, thermal stability, corrosion resistance, electrical conductivity, and compatibility. The material must be able to resist deformation, fracture, and fatigue under expected loads and stresses, maintain its integrity and functionality under expected temperature ranges and thermal cycles, resist chemical attack and deterioration from exposure to the fluid, environment, and cleaning agents, have a low electrical conductivity to avoid sparking and electrostatic discharge, and be compatible with the fluid, gaskets, seals, and other components of the equipment.

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Saeed Moshayedi

Deputy Head Of Inspection Department at 6th Refinery of South Pars Gas Complex
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In a nutshell, determining potential damage mechanisms in which medium and material of construction might interact, is of essential matters in prediction of failures of any system.

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2 Material selection

The next step is to select the material that meets the requirements and specifications for the equipment. There are various types of materials that can be used for piping and valves in explosive environments, such as metals, plastics, and composites. Metals are typically chosen for their high strength, durability, and versatility, but can be prone to corrosion, sparking, and thermal expansion. Plastics are often selected due to their low cost, light weight, and corrosion resistance; however they can be susceptible to deformation, cracking, and melting. Composites combine two or more different materials to achieve improved properties such as high strength, low weight, and corrosion resistance but can be expensive, complex, and difficult to repair. Suitable materials for explosive environments include stainless steel, carbon steel, aluminum, copper, nickel alloys, polyethylene, polypropylene, polyvinyl chloride, fluoropolymers, fiberglass, carbon fiber and epoxy resin.

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3 Material testing

The final step is to test the material to verify its suitability and reliability for the equipment. Testing can involve a variety of methods and procedures, such as mechanical testing to evaluate the material's resistance to tension, compression, bending, impact, and fatigue; thermal testing to examine the material's behavior under different temperatures and thermal cycles; corrosion testing to assess the material's resistance to chemical attack and deterioration; electrical testing to determine the material's conductivity, resistance, and capacitance; and compatibility testing to assess the material's interaction with the fluid, gaskets, seals, and other components of the equipment.

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4 Material standards

In addition to material properties, selection, and testing, it is important to follow the material standards applicable for the equipment and explosive environment. These standards define the material's quality, performance, and safety. For instance, ASME B31.3 covers design and installation of process piping systems for chemical plants and petroleum refineries. API 6A covers specification and testing of valves and wellhead equipment for oil and gas production. ATEX is a European directive that covers equipment and protective systems intended for use in explosive atmospheres, while IECEx is an international certification scheme for equipment and services in explosive atmospheres. By following these steps and standards, you can select the best materials for your equipment in explosive environments. This can improve performance, safety, lifespan, as well as reduce risks of accidents and failures.

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5 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?

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How can you select materials for equipment in explosive environments?

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1 Material properties

2 Material selection

3 Material testing

4 Material standards

5 Here’s what else to consider

Chemical Engineering

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